The invention relates to an attachment used in connection with ultrasound transducers for certain surgical procedures in which a needle, biopsy instrument or catheter is inserted into an internal organ of the patient.
Diagnostic ultrasound equipment uses sound waves of a very high frequency directed into the body via a piezoelectric crystal transducer. As the sound waves penetrate the body, they will be reflected back to the transducer from various organs. These returning "echos" produce a cross-sectional image of the human body being scanned. Initially, almost all ultrasound practices had been conducted with static imaging systems which produce a single, static image. Use of static scanners was preferred over "real-time" scanners because of the higher quality of the image produced by the static scanner. However, because of advances in electronic technology, the image quality of the real-time scanner is now comparable to that of the best static scanner, and thus real-time scanners are being used with increasing frequency. These real-time scanners present two dimensional information as it happens because the tissue being examined is rapidly and repeatedly scanned producing information that is displayed on a conventional cathode-ray tube or screen. The observer therefore summates many images each second and sees them as a continuous image on the screen. There are various types of real-time scanners, and the sector-type scanner provides an image over a wider range than the linear-type scanners.
With these improved ultrasound scanners, diagnostic procedures are becoming available to explore and evaluate almost any part of the human anatomy. Diagnostic ultrasound is becoming the exclusive technique for obstetrical imaging because it does not involve any radiation danger to the mother or the growing fetus. For this reason, amniocentesis is becoming increasingly used as a diagnostic aid by obstetricians. However, because of the dynamics of both the uterus and the fetus, it is imperative that amniocentesis be performed at the same time as sonography, and even so, it is possible to accidentally strike the fetus with the needle during the procedure. This is true notwithstanding good visual control in the scanning region, since up to the time the needle enters the scanned area, the puncturing sequence must be carried out blindly. If penetration is not correct, the needle or cannula must be withdrawn and reinserted causing additional invasive trauma to the patient.
To improve the accuracy of penetration, there have been designed various devices for assisting in guiding the needle, cannula or catheter into the selected body site. Many of these guides are fixed and the angle of penetration is somewhat indirect thus detracting from the accuracy of penetrating the ultimate target site within the body of the patient. Tolerances are very close particularly when the site involves a dynamic organ and a moving fetus. Moreover, some of these devices require the use of a cannula, which increases the trauma to the patient, and because of its relatively large size, requires greater accuracy of penetration. There is therefore a need for an improved guide which will improve the precision of penetration to the ultimate target site within the body of the patient. There is also a need for a device which will allow easy adjustability of the angle of penetration and permit the needle to move once penetration has occurred if the target site moves. There is a further need for a device which will allow the needle or catheter to remain in place in the body part while allowing easy removal of the transducer and guide. There is a further need for a simple and inexpensive device that can be easily accommodated to needles and catheters of various sizes.